Internal combustion engines utilize many types of fuel injection such as manifold injection, port injection and direct injection. Direct injection engines have a fuel feed system that injects fuel directly into the combustion chamber of the engine. Direct injection engines employ high pressure fuel systems in order to more fully atomize the fuel in the combustion chamber. At start-up of the engine, it is desirable to have the operating pressure of the fuel system be at a sufficient level to achieve proper atomization to sustain low emission levels. It generally requires a number of engine revolutions before the fuel system attains the desired pressure level. This delays the engine start-up.
To alleviate this condition, it has been proposed to install a passive high pressure accumulator to the fuel system such that fuel is stored at the desired pressure between engine shut-off and the next engine start-up. These systems have two drawbacks. The storage of high pressure fuel is undesirable and the accumulators often "leak down" between shut-down and start-up, if the period is long, thereby defeating the purpose of the accumulator.